Ada County is in Southwestern Idaho. Of the 44 counties in the Gem State, 678,764-acre Ada County ranks 31st by size. A recent survey of Land Network data shows nearly 1,000 acres of residential land and property for sale in Idaho's Ada County, which is valued at a combined $360 million. The average price of residential land for sale in Ada County was $2 million. Browse all residential land and rural property for sale in Idaho to find residential land and properties that suit your lifestyle needs, from existing residential homes and estates to land ready for future residential-property development.